Eccentric vs Concentric Contractions

As therapists, we understand so much about the human body and how it functions. It's important to realize, however, that our ultimate goal is also to educate our patients. This allows us to empower those seeking our help instead of creating reliance. Provide them the tools they need to begin taking control of their movement. At the very least, if we're diligent about explaining our thought processes and why certain aspects of treatment are important, we have patients who are more involved in their health, who understand the treatment process, and who have greater trust in us as clinicians.

As physical therapists, we understand that our muscles act in many ways: statically or dynamically, quickly or slowly, voluntarily or involuntarily. This may not be so obvious for our patients. One concept I continually stress is that of eccentric and concentric contractions. It's a topic that most of us probably take for granted, but an effective explanation can make all the difference when it comes to patient buy in.

Let's begin with defining three terms:

🔹Isometric Contractions: When a muscle produces force without changing length.

🔸Concentric Contractions: When a muscle produces force and shortens.

🔹Eccentric Contractions: When a muscle produces force and lengthens.

These are the classic definitions, and many of us explain this to our patients, but a simple tweak may enhance their understanding.

In reality, we can think of the eccentric contraction in an exercise as the deceleration phase and the concentric contraction as the acceleration phase. This adjustment in terminology can allow us to simplify things for our athletes and improve communication over our course of care.

This simple tweak becomes much easier to understand:

  • In a bicep curl:

    • As you curl the weight, you're performing a CONCENTRIC CONTRACTION, and your bicep is ACCELERATING the load upwards against gravity.

    • As you slowly lower the weight, gravity is accelerating the weight towards the ground. Your bicep must contract ECCENTRICALLY, producing force as it lengthens, and effectively DECELERATING the weight as gravity pulls it to the floor.

  • For an audiovisual example, take a look at the clip below applying this concept to the hamstrings during a Romanian Deadlift.

Remember, the more effectively you can communicate with your clientele, the more effective of an educator you will be. It's these little things that can make a huge difference in your success as a clinician.